Mirror unit

ABSTRACT

In a mirror unit, a first wall portion is higher than a second wall portion. A window member is disposed on a top surface of the first wall portion and a top surface of the second wall portion and is inclined with respect to a mirror surface. When any one of first to fourth wall portions is set as a first reference wall portion, in a cross-section perpendicular to the first reference wall portion, a first line passing through a first end at a side of the first reference wall portion in the mirror surface and a first corner portion formed at the side of the first reference wall portion by an outer surface and a first side surface in the window member intersects the first wall portion. A wiring portion includes a portion extending inside a base and leads outside a frame member.

TECHNICAL FIELD

An aspect of the present disclosure relates to a mirror unit.

BACKGROUND

Japanese Unexamined Patent Publication No. 2017-215352 discloses amirror unit including an optical scanning device having a mirror surfaceprovided on a movable portion, a frame member disposed so as to surroundthe optical scanning device, and a flat window member covering anopening of the frame member. Light is incident to the mirror surfacethrough the window member from the outside, is reflected by the mirrorsurface, and is emitted to the outside through the window member.

SUMMARY

In the mirror unit described in Japanese Unexamined Patent PublicationNo. 2017-215352, a height of one of a pair of wall portions constitutingthe frame member and facing each other is formed to be higher than theother and the window member disposed on the frame member is inclinedwith respect to the mirror surface. When the window member is inclinedwith respect to the mirror surface, the traveling direction of the lightreflected by the window member can be different from the travelingdirection of the light reflected by the mirror surface and the lightreflected by the window member can be prevented from to be noise light.

Meanwhile, in the configuration in which optical scanning is performedby swinging the movable portion provided with the mirror surface as inthe mirror unit, the light incident angle to the window member increasesin accordance with the angle of the mirror surface and the refractionangle of the light emitted from the window member increases.Particularly, in the above-described configuration in which the windowmember is inclined, the light incident angle to the window memberfurther increases. For that reason, it is necessary to consider theinfluence of refraction at the window member in order to realizehigh-accuracy optical scanning Here, it is conceivable to restrain theinfluence of refraction at the window member by thinning the windowmember to reduce the refraction amount at the window member. However,when the window member is formed to be thin, the strength of the windowmember decreases and the window member is likely to be broken. For thatreason, it is required to prevent the damage of the window member.Further, it is also required to improve reliability in theabove-described mirror unit.

An object of an aspect of the present disclosure is to provide a mirrorunit capable of preventing damage of a window member while reducingnoise light and improving reliability.

A mirror unit according to an aspect of the present disclosure includes:a base; an optical scanning device that includes a movable portion and amirror surface provided on the movable portion and is disposed on thebase; a frame member disposed on the base so as to surround the opticalscanning device when viewed from a first direction; a window memberformed in a plate shape and disposed on the frame member so as to coveran opening of the frame member; and a wiring portion electricallyconnected to the optical scanning device, in which the frame memberincludes a first wall portion and a second wall portion which face eachother in a second direction perpendicular to the first direction and athird wall portion and a fourth wall portion which face each other in athird direction perpendicular to both the first direction and the seconddirection, in which a height of the first wall portion is higher than aheight of the second wall portion, in which the window member isdisposed on a top surface of the first wall portion and a top surface ofthe second wall portion and is inclined with respect to the mirrorsurface, in which when any one of the first wall portion, the secondwall portion, the third wall portion, and the fourth wall portion is setas a first reference wall portion, in a cross-section passing throughthe mirror surface and perpendicular to the first reference wallportion, a first line passing through a first end at a side of the firstreference wall portion in the mirror surface and a first corner portionformed at the side of the first reference wall portion by an outersurface opposite to the frame member and a first side surface in thewindow member intersects the first reference wall portion, and in whichthe wiring portion includes a portion extending inside the base andleads outside the frame member.

In the mirror unit, the height of the first wall portion is higher thanthe height of the second wall portion and the window member is disposedon the top surface of the first wall portion and the top surface of thesecond wall portion and is inclined with respect to the mirror surface.Accordingly, the traveling direction of the light reflected by thewindow member can be different from the traveling direction of the lightreflected by the mirror surface and the light reflected by the windowmember can be prevented from to be noise light. Further, when any one ofthe first wall portion, the second wall portion, the third wall portion,and the fourth wall portion is set as the first reference wall portion,in the cross-section passing through the mirror surface andperpendicular to the first reference wall portion, the first linepassing through the first end at the side of the first reference wallportion in the mirror surface and the first corner portion formed at theside of the first reference wall portion by the outer surface and thefirst side surface in the window member intersects the first referencewall portion. Since the first line is formed so as to intersect thefirst wall portion, the first reference wall portion is formed to berelatively thicker with respect to the window member. Accordingly, it ispossible to support the window member by the thick first reference wallportion and to prevent the damage of the window member. Meanwhile, whenthe first reference wall portion is formed to be thick, it isconceivable to widen the thickness of the first reference wall portiontoward the optical scanning device from the viewpoint ofminiaturization. However, in that case, the area of the portion locatedat the inside of the frame member on the base is narrowed. When a wiringportion for electrical connection to the optical scanning device isformed in such a narrow portion, there is concern that defects such asshort circuit or the like may occur in the wiring portion. In contrast,in the mirror unit, the wiring portion includes a portion extendinginside the base and leads outside the frame member. Since the wiringportion is formed inside the base as such, it is possible to preventdefects such as short circuit or the like in the wiring portion.Further, for example, compared to a case in which the wiring portion isformed so as to extend along the surface of the base between the baseand the frame member, the deterioration of the wiring portion can beprevented and the influence of the wiring portion on the bonding portionbetween the base and the frame member can be prevented. Thus, accordingto the mirror unit, it is possible to prevent the damage of the windowmember while reducing noise light and to improve the reliability.

The window member may be bonded to the frame member and a thickness ofthe window member may be smaller than a width of a region in which thewindow member and the frame member are bonded to each other. In thiscase, the window member can be formed to be thin and hence the influenceof refraction at the window member can be restrained.

When one facing the first reference wall portion among the first wallportion, the second wall portion, the third wall portion, and the fourthwall portion is set as a second reference wall portion, in thecross-section, a second line passing through a second end at a side ofthe second reference wall portion in the mirror surface and a secondcorner portion formed at the side of the second reference wall portionby the outer surface and a second side surface in the window member mayintersect the second reference wall portion. In this case, since thesecond reference wall portion is formed to be relatively thicker withrespect to the window member, it is possible to support the windowmember by the thick second reference wall portion and to furtherreliably prevent the damage of the window member.

The wiring portion may extend inside the base so as to overlap the firstreference wall portion when viewed from the first direction. When thewiring portion is to be pulled out toward the thick first reference wallportion, the above-described deterioration of the wiring portion or thelike tends to occur. However, in the mirror unit, since the wiringportion is formed inside the base, it is possible to reliably preventdeterioration of the wiring portion or the like.

The wiring portion may include an electrode pad provided on the base ina region located at an inside of the frame member when viewed from thefirst direction, when one facing the first reference wall portion amongthe first wall portion, the second wall portion, the third wall portion,and the fourth wall portion is set as a second reference wall portion, adistance between the optical scanning device and the first referencewall portion may be longer than a distance between the optical scanningdevice and the second reference wall portion, and the electrode pad maybe disposed between the optical scanning device and the first referencewall portion on the base. In this case, it is possible to ensure a spacefor disposing the electrode pad.

The first reference wall portion may be the first wall portion and thesecond reference wall portion may be the second wall portion. In thiscase, since the first wall portion is separated from the opticalscanning device compared to the second wall portion, it is possible toprevent the light reflected by the mirror surface from being interruptedby the first wall portion higher than the second wall portion.

The wiring portion may be electrically connected to the optical scanningdevice in a first region located at an inside of the frame member whenviewed from the first direction, extend inside the base in a secondregion overlapping the frame member when viewed from the firstdirection, and leads out to a third region located at an outside of theframe member when viewed from the first direction. In this case, it ispossible to further reliably prevent deterioration of the wiring portionor the like.

According to an aspect of the present disclosure, it is possible toprovide a mirror unit capable of preventing damage of a window memberwhile reducing noise light and improving reliability.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view of a mirror unit according to an embodiment.

FIG. 2 is a cross-sectional view taken along a line II-II of FIG. 1.

FIG. 3 is a cross-sectional view taken along a line of FIG. 1.

FIG. 4 is a cross-sectional view taken along a line IV-IV of FIG. 1.

FIG. 5 is a plan view of an optical scanning device.

FIG. 6 is a cross-sectional view of a mirror unit according to amodified example.

DETAILED DESCRIPTION

Hereinafter, an embodiment of the present disclosure will be describedin detail with reference to the drawings. In the description below, thesame or corresponding components will be denoted by the same referencenumerals and redundant description will be omitted.

[Overall Configuration of Mirror Unit]

As illustrated in FIG. 1, a mirror unit 100 includes an optical scanningdevice 1 and a package 40 accommodating the optical scanning device 1.The package 40 includes a base 42, a frame member 43, and a windowmember 44.

The base 42 is formed in a rectangular plate shape from, for example, anon-magnetic material such as aluminum nitride or aluminum oxide. Thebase 42 includes a main surface 42 a and a rear surface 42 b on the sideopposite to the main surface 42 a. The main surface 42 a is a surfaceconstituting a part of the inner surface of the package 40. The mainsurface 42 a is provided with a depression 42 c. A bottom surface of thedepression 42 c is provided with a depression 42 d. The optical scanningdevice 1 is disposed on the base 42, more specifically, a bottom surfaceof the depression 42 c. A magnetic field generating unit (notillustrated) which generates a magnetic field acting on a first drivecoil 11 and a second drive coil 12 of the optical scanning device 1 tobe described later is disposed on the side of the rear surface 42 b ofthe base 42. The magnetic field generating unit includes, for example,permanent magnets in a Halbach array.

The frame member 43 is disposed on the main surface 42 a so as tosurround the optical scanning device 1 (to surround a mirror surface 7 ato be described later) when viewed from the Z-axis direction (the firstdirection) perpendicular to the main surface 42 a of the base 42. Theframe member 43 is formed in a rectangular frame shape from, forexample, a non-magnetic material such as aluminum nitride or aluminumoxide.

The window member 44 is configured by, for example, forming ananti-reflection film on both surfaces of a rectangular plate basematerial formed of a light-transmitting material such as glass. Thewindow member 44 is disposed on the frame member 43 so as to cover oneopening 43 a of the frame member 43 and faces the base 42 and theoptical scanning device 1 in the Z-axis direction. The window member 44is bonded to the frame member 43 by, for example, a bonding material 45such as low-melting glass so as to hermetically seal the opening 43 a.

The base 42 is bonded to the frame member 43 by, for example, a bondingmaterial 46 such as low-melting glass so as to hermetically seal theother opening 43 b of the frame member 43. Accordingly, the inside ofthe package 40 is hermetically sealed. The base 42 and the frame member43 may be integrally formed so as to configure a single member.

The bonding with the bonding materials 45 and 46 is not limited to thebonding with the low-melting glass and may be, for example, bonding withresin adhesive, low-temperature solder (Sn/Pb or Sn/Cu-based),low-temperature brazing material (Au/Sn alloy, Au/Ge alloy, or thelike), high-temperature brazing material (Ag-based or the like),projection welding, seam seal welding, laser welding, electron beamwelding, or the like.

[Configuration of Optical Scanning Device]

As illustrated in FIG. 2, the optical scanning device 1 includes asupport portion 2 and a movable portion 10 which is swingable withrespect to the support portion 2. The movable portion 10 includes afirst movable portion 3, a second movable portion 4, a pair of firstconnection portions 5, a pair of second connection portions 6, and amirror 7. The support portion 2, the first movable portion 3, the secondmovable portion 4, the pair of first connection portions 5, and the pairof second connection portions 6 are integrally formed by, for example, aSilicon on Insulator (SOI) substrate. That is, the optical scanningdevice 1 is configured as a Micro Electro Mechanical Systems (MEMS)device.

The first movable portion 3 is formed in, for example, a rectangularplate shape. The second movable portion 4 is formed in, for example, arectangular ring shape so as to surround the first movable portion 3with a gap when viewed from an optical axis direction A. The supportportion 2 is formed in, for example, a rectangular ring shape so as tosurround the second movable portion 4 with a gap when viewed from theoptical axis direction A. That is, the support portion 2 is formed in aframe shape so as to surround the first movable portion 3 and the secondmovable portion 4 when viewed from the optical axis direction A.

The first movable portion 3 is connected to the second movable portion 4via the pair of first connection portions 5 so as to be swingable arounda first axis X1. That is, the first movable portion 3 is supported bythe support portion 2 so as to be swingable around the first axis X1.The first movable portion 3 includes a first portion 31 and a secondportion 32. The first portion 31 is formed in, for example, a circularshape when viewed from the optical axis direction A. The second portion32 is formed in, for example, a rectangular ring shape when viewed fromthe optical axis direction A. The first portion 31 is surrounded by thesecond portion 32 when viewed from the optical axis direction A and isconnected to the second portion 32 via a plurality of (in this example,two) connection portions 33. That is, gaps are formed between the firstportion 31 and the second portion 32 except for the plurality ofconnection portions 33.

The connection portion 33 is located, for example, at the center of twosides of the rectangular inner edge of the second portion 32intersecting a second axis X2. That is, in this example, the connectionportion 33 is located on the second axis X2. The first portion 31 may beconnected to the second portion 32 in a direction along at least thesecond axis X2.

The second movable portion 4 is connected to the support portion 2 viathe pair of second connection portions 6 so as to be swingable aroundthe second axis X2. That is, the second movable portion 4 is supportedby the support portion 2 so as to be swingable around the second axisX2. The first axis X1 and the second axis X2 are perpendicular to theoptical axis direction A and intersect each other (orthogonal to eachother in this example). The first portion 31 may be formed in arectangular shape or polygonal shape when viewed from the optical axisdirection A. The first portion 31 may be formed in a circular shape (forexample, an oval shape) when viewed from the optical axis direction A.The second portion 32 may be formed in a ring shape or a polygonal ringshape of a pentagon or more when viewed from the optical axis directionA.

The pair of first connection portions 5 are disposed on the first axisX1 so as to sandwich the first movable portion 3 in a gap between thesecond movable portion 4 and the second portion 32 of the first movableportion 3. Each first connection portion 5 functions as a torsion bar.The pair of second connection portions 6 is disposed on the second axisX2 so as to sandwich the second movable portion 4 in a gap between thesecond movable portion 4 and the support portion 2. Each secondconnection portion 6 functions as a torsion bar.

The mirror 7 is provided on the first portion 31 of the first movableportion 3. The mirror 7 is formed on the surface at the side opposite tothe base 42 (at the side of the window member 44) in the first portion31 so as to include an intersection point between the first axis X1 andthe second axis X2. For example, the mirror 7 is formed in a circular,oval, or rectangular film shape from a metal material such as aluminum,an aluminum-based alloy, gold, or silver. A surface at the side oppositeto the first movable portion 3 in the mirror 7 constitutes the mirrorsurface 7 a extending in a direction perpendicular to the optical axisdirection A. The center (geometric center, centroid) of the mirrorsurface 7 a matches the intersection between the first axis X1 and thesecond axis X2 when viewed from the optical axis direction A. In thisway, since the mirror 7 is provided on the first portion 31 connected tothe second portion 32 through the plurality of connection portions 33,deformation such as bending of the mirror 7 can be prevented even whenthe first movable portion 3 swings around the first axis X1 at theresonant frequency level.

The distance from the outer edge of the mirror surface 7 a to the outeredge of the first portion 31 is smaller than the width of the connectionportion 33. The width of the connection portion 33 is the length in adirection (in this example, a direction along the first axis X1)perpendicular to the extension direction of the connection portion 33(in this example, a direction along the second axis X2). The firstmovable portion 3 may not include the second portion 32 and theconnection portion 33. The distance from the outer edge of the mirrorsurface 7 a to the outer edge of the first portion 31 may be smallerthan the width of the second connection portion 6. The width of thesecond connection portion 6 is the length in a direction (in thisexample, a direction along the first axis X1) perpendicular to theextension direction of the second connection portion 6 (in this example,a direction along the second axis X2).

Further, the optical scanning device 1 includes a first drive coil 11, asecond drive coil 12, wirings 15 a and 15 b, wirings 16 a and 16 b,electrode pads 21 a and 21 b, and electrode pads 22 a and 22 b. In FIG.2, for convenience of description, the first drive coil 11 and thesecond drive coil 12 are indicated by a one dotted chain line and thewirings 15 a and 15 b and the wirings 16 a and 16 b are indicated by asolid line.

The first drive coil 11 is provided in the second portion 32 of thefirst movable portion 3. The first drive coil 11 is wound a plurality oftimes in a spiral shape (a swirl shape) in a region outside the mirror 7(that is, the second portion 32) when viewed from the optical axisdirection A. A magnetic field generated by the magnetic field generatingunit acts on the first drive coil 11.

The first drive coil 11 is disposed in a groove formed on the surface ofthe first movable portion 3. That is, the first drive coil 11 is buriedin the first movable portion 3. One end of the first drive coil 11 isconnected to the electrode pad 21 a through the wiring 15 a. The wiring15 a extends from the first movable portion 3 to the support portion 2through one first connection portion 5, the second movable portion 4,and one second connection portion 6. For example, the wiring 15 a andthe electrode pad 21 a are integrally formed of a metal material such astungsten, aluminum, gold, silver, copper, or an aluminum-based alloy.

The other end of the first drive coil 11 is connected to the electrodepad 21 b through the wiring 15 b. The wiring 15 b extends from the firstmovable portion 3 to the support portion 2 through the other firstconnection portion 5, the second movable portion 4, and the other secondconnection portion 6. For example, the wiring 15 b and the electrode pad21 b are integrally formed of a metal material such as tungsten,aluminum, gold, silver, copper, or an aluminum-based alloy.

The second drive coil 12 is provided in the second movable portion 4.The second drive coil 12 is wound a plurality of times in a spiral shape(a swirl shape) in the second movable portion 4. A magnetic fieldgenerated by the magnetic field generating unit acts on the second drivecoil 12. The second drive coil 12 is disposed in a groove formed on thesurface of the second movable portion 4. That is, the second drive coil12 is buried in the second movable portion 4.

One end of the second drive coil 12 is connected to the electrode pad 22a through the wiring 16 a. The wiring 16 a extends from the secondmovable portion 4 to the support portion 2 through one second connectionportion 6. For example, the wiring 16 a and the electrode pad 22 a areintegrally formed of a metal material such as tungsten, aluminum, gold,silver, copper, or an aluminum-based alloy.

The other end of the second drive coil 12 is connected to the electrodepad 22 b through the wiring 16 b. The wiring 16 b extends from thesecond movable portion 4 to the support portion 2 through the othersecond connection portion 6. For example, the wiring 16 b and theelectrode pad 22 b are integrally formed of a metal material such astungsten, aluminum, gold, silver, copper, or an aluminum-based alloy.

The number and arrangement of the electrode pads 21 a, 21 b, 22 a, and22 b are not limited to the example illustrated in FIG. 4. As in theexample of FIG. 4, the electrode pad 21 a may be disposed at one side ofthe second axis X2 with respect to the movable portion 10 and theelectrode pad 21 b may be disposed at the other side of the second axisX2 with respect to the movable portion 10. Alternatively, both theelectrode pads 21 a and 21 b may be disposed at one side or the otherside of the second axis X2 with respect to the movable portion 10. Inthe latter case, the wirings 15 a and 15 b may extend on the same secondconnection portion 6. These points are the same in the electrode pads 22a and 22 b and the wirings 16 a and 16 b.

Hereinafter, first to fifth examples will be described as an operationexample of the movable portion 10 of the optical scanning device 1. Inthe first example, a high-frequency drive current is applied to thefirst drive coil 11. At this time, since a magnetic field generated bythe magnetic field generating unit acts on the first drive coil 11, aLorentz force is generated in the first drive coil 11. Accordingly, thefirst movable portion 3 is swung around the first axis X1, for example,at the resonant frequency level.

Further, a drive current of a certain magnitude is applied to the seconddrive coil 12. At this time, since a magnetic field generated by themagnetic field generating unit acts on the second drive coil 12, aLorentz force is generated in the second drive coil 12. Accordingly, thesecond movable portion 4 is rotated around the second axis X2, forexample, in response to the magnitude of the drive current and isstopped at that state. Accordingly, according to the optical scanningdevice 1, light emitted from a predetermined light source can be scannedwhile being reflected by the mirror surface 7 a. Light is incident tothe mirror surface 7 a through the window member 44 from the outside, isreflected by the mirror surface 7 a, and is emitted to the outsidethrough the window member 44. In the first example, the first movableportion 3 is swung at the resonant frequency and the second movableportion 4 is used statically.

In the second example, similarly to the operation of the first movableportion 3 of the first example, the first movable portion 3 is swung inresponse to the resonant frequency when a high-frequency drive currentis applied to the first drive coil 11 and the second movable portion 4is swung in response to the resonant frequency when a high-frequencydrive current is applied to the second drive coil 12. In this way, inthe second example, both the first movable portion 3 and the secondmovable portion 4 are swung at the resonant frequency.

In the third example, similarly to the operation of the second movableportion 4 of the first example, the first movable portion 3 is rotatedand stopped around the first axis X1 in response to the magnitude of thedrive current when a drive current of a certain magnitude is applied tothe first drive coil 11 and the second movable portion 4 is rotated andstopped around the second axis X2 in response to the magnitude of thedrive current when a drive current of a certain magnitude is applied tothe second drive coil 12. In this way, in the third example, both thefirst movable portion 3 and the second movable portion 4 are usedstatically.

In the fourth example and the fifth example, only the first movableportion 3 is driven. In the fourth example, since a high-frequency drivecurrent is applied to the first drive coil 11, the first movable portion3 is swung in response to the resonant frequency. In the fifth example,since a drive current of a certain magnitude is applied to the firstdrive coil 11, the first movable portion 3 is rotated and stopped aroundthe first axis X1 in response to the magnitude of the drive current. Thefourth example and the fifth example can be used, for example, in a casein which the second movable portion 4 is not provided or the like.

As described above, the optical scanning device 1 is disposed on thebase 42. The support portion 2 is fixed to the bottom surface of thedepression 42 c and the first movable portion 3 and the second movableportion 4 face the bottom surface of the depression 42 d. Since thedepression 42 d is provided, the first movable portion 3 and the secondmovable portion 4 can swing without interfering with the base 42.

[Configuration of Package]

As illustrated in FIGS. 1 and 3, the frame member 43 includes a firstwall portion 51, a second wall portion 52, a third wall portion 53, anda fourth wall portion 54. Each of the wall portions 51 to 54 is formedin a plate shape and has the same thickness. The first wall portion 51and the second wall portion 52 extend in parallel to each other and faceeach other in the X-axis direction (the second direction) perpendicularto the Z-axis direction. The third wall portion 53 and the fourth wallportion 54 extend in parallel to each other and face each other in theY-axis direction (the third direction) perpendicular to both the Z-axisdirection and the X-axis direction. The third wall portion 53 isconnected to one end of the first wall portion 51 and one end of thesecond wall portion 52 and the fourth wall portion 54 is connected tothe other end of the first wall portion 51 and the other end of thesecond wall portion 52. The third wall portion 53 and the fourth wallportion 54 have, for example, the same shape.

A top surface 51 a at the side opposite to the base 42 in the first wallportion 51 is inclined with respect to the main surface 42 a so as tomove away from the main surface 42 a of the base 42 as it goes away fromthe second wall portion 52. A top surface 52 a at the side opposite tothe base 42 in the second wall portion 52 is inclined with respect tothe main surface 42 a so as to move away from the main surface 42 a ofthe base 42 as it goes toward the first wall portion 51. A height H1 ofthe first wall portion 51 is higher than a height H2 of the second wallportion 52. The height H1 of the first wall portion 51 is a maximumvalue of the distance from the main surface 42 a to the top surface 51 aand the height H2 of the second wall portion 52 is a maximum value fromthe main surface 42 a to the top surface 52 a.

A top surface 53 a at the side opposite to the base 42 in the third wallportion 53 is inclined with respect to the main surface 42 a so as tomove away from the main surface 42 a of the base 42 as it goes towardthe first wall portion 51 when viewed from the Y-axis direction. A topsurface 54 a at the side opposite to the base 42 in the fourth wallportion 54 is inclined with respect to the main surface 42 a so as tomove away from the main surface 42 a of the base 42 as it goes towardthe first wall portion 51 when viewed from the Y-axis direction.

The top surfaces 51 a to 54 a are flush with one other and located onthe same plane. The window member 44 is disposed on the top surfaces 51a to 54 a and is inclined with respect to the main surface 42 a (themirror surface 7 a) so as to move away from the main surface 42 a as itgoes from the second wall portion 52 toward the first wall portion 51.In other words, each of the top surfaces 51 a to 54 a is inclinedcorresponding to an angle of the inclination of the window member 44.

The first wall portion 51 may be formed by a plurality of portions.These portions may be formed separately with a gap providedtherebetween. In the embodiment, the entire top surface 51 a is formedflat, but the top surface 51 a may be divided into a plurality ofregions by forming a notch, a depression, a convex portion, or the likeon the top surface 51 a. The entire top surface 51 a does not need to beinclined at an angle corresponding to the inclination of the windowmember 44. For example, a line connecting two points in the top surface51 a may be inclined at an angle corresponding to the inclination of thewindow member 44. These matters are the same for the second wall portion52 to the fourth wall portion 54. The window member 44 may not be bondedto the frame member 43 in the entire top surfaces 51 a to 54 a and maybe boded to the frame member 43 in at least a part of the top surfaces51 a to 54 a.

The window member 44 includes an outer surface 44 a, an inner surface 44b, a first side surface 44 c, a second side surface 44 d, a third sidesurface 44 e, and a fourth side surface 44 f. The outer surface 44 a isa surface at the side opposite to the frame member 43 and the innersurface 44 b is a surface at the side of the frame member 43. The outersurface 44 a and the inner surface 44 b extend in parallel to eachother. Each of the side surfaces 44 c to 44 f extends in a directionperpendicular to the outer surface 44 a and the inner surface 44 b andis continuous to the outer surface 44 a and the inner surface 44 b. Thewindow member 44 is disposed on the frame member 43 so that the innersurface 44 b faces the top surfaces 51 a to 54 a. The first side surface44 c, the second side surface 44 d, the third side surface 44 e, and thefourth side surface 44 f are respectively located on the top surface 51a, the top surface 52 a, the top surface 53 a, and the top surface 54 a.

The window member 44 includes a first corner portion 61 formed at theside of the first wall portion 51 by the outer surface 44 a and thefirst side surface 44 c, a second corner portion 62 formed at the sideof the second wall portion 52 by the outer surface 44 a and the secondside surface 44 d, a third corner portion 63 formed at the side of thethird wall portion 53 by the outer surface 44 a and the third sidesurface 44 e, and a fourth corner portion 64 formed at the side of thefourth wall portion 54 by the outer surface 44 a and the fourth sidesurface 44 f. When viewed from the Z-axis direction, the first cornerportion 61 overlaps the top surface 51 a and the second corner portion62 overlaps the top surface 52 a. When viewed from the Z-axis direction,the third corner portion 63 overlaps the top surface 53 a and the fourthcorner portion 64 overlaps the top surface 54 a. In this example, thefirst side surface 44 c is a flat surface, but the first side surface 44c may be a curved surface. In this case, the first corner portion 61 isformed at a boundary part between the flat outer surface 44 a and thecurved first side surface 44 c. Similarly, the second side surface 44 dmay be a curved surface. In this case, the second corner portion 62 isformed at a boundary part between the flat outer surface 44 a and thecurved second side surface 44 d.

A thickness T44 of the window member 44 is thinner than each of athickness T51 of the first wall portion 51, a thickness T52 of thesecond wall portion 52, a thickness T53 of the third wall portion 53,and a thickness T54 of the fourth wall portion 54. In this example, thethicknesses T51 to T54 of the wall portions 51 to 54 are the same.Further, the thickness T44 of the window member 44 is smaller than awidth W of a bonding region in which the window member 44 and the framemember 43 are bonded to each other by a bonding material 45. The width Wis a width in a direction parallel to each of the top surfaces 51 a to54 a and orthogonal to the extension direction of the frame member 43.In this example, the width W of the bonding region is the same along theentire periphery of the frame member 43, but when the width of thebonding region changes in the circumferential direction of the framemember 43, the width W is a maximum value of the width of the bondingregion.

A positional relationship of respective members will be described withreference to FIGS. 2 and 3. The optical scanning device 1 is disposed,for example, so that the first axis X1 is parallel to the X-axisdirection and the second axis X2 is parallel to the Y-axis direction.FIG. 2 illustrates a cross-section parallel to both the X-axis directionand the Z-axis direction and passing through the center of the mirrorsurface 7 a. The cross-section of FIG. 2 is perpendicular to the Y-axisdirection and is perpendicular to the first wall portion 51 and thesecond wall portion 52. FIG. 3 illustrates a cross-section parallel toboth the Y-axis direction and the Z-axis direction and passing throughthe center of the mirror surface 7 a. The cross-section of FIG. 3 isperpendicular to the X-axis direction and is perpendicular to the thirdwall portion 53 and the fourth wall portion 54.

FIGS. 2 and 3 illustrate a non-rotation state (a non-drive state and aninitial state) in which the movable portion 10 does not rotate aroundthe first axis X1 and the second axis X2. In the non-rotation state, thefirst movable portion 3 does not rotate around the first axis X1 and thesecond movable portion 4 does not around the second axis X2. In thenon-rotation state, the mirror surface 7 a is parallel to the mainsurface 42 a of the base 42.

In the cross-section of FIG. 2, a first line L1 which passes through afirst end P1 corresponding to an end portion at the side of the firstwall portion 51 in the mirror surface 7 a and a vertex of the firstcorner portion 61 intersects the first wall portion 51. That is, thefirst line L1 passes through the first wall portion 51. Further, in thecross-section of FIG. 2, a second line L2 which passes through a secondend P2 corresponding to an end portion at the side of the second wallportion 52 in the mirror surface 7 a and a vertex of the second cornerportion 62 intersects the second wall portion 52. That is, the secondline L2 passes through the second wall portion 52.

In the cross-section of FIG. 3, a third line L3 which passes through athird end P3 corresponding to an end portion at the side of the thirdwall portion 53 in the mirror surface 7 a and a vertex of the thirdcorner portion 63 intersects the third wall portion 53. That is, thethird line L3 passes through the third wall portion 53. Further, in thecross-section of FIG. 3, a fourth line L4 which passes through a fourthend P4 corresponding to an end portion at the side of the fourth wallportion 54 in the mirror surface 7 a and a vertex of the fourth cornerportion 64 intersects the fourth wall portion 54. That is, the fourthline L4 passes through the fourth wall portion 54.

when the mirror surface 7 a is formed by mirror-finishing the surface ofthe first movable portion 3, the end portion of the mirror surface 7 ais the end portion of the processed region. Alternatively, when areflection film is not formed and the surface itself of the firstmovable portion 3 constitutes the mirror surface 7 a, the end portion ofthe mirror surface 7 a is the end portion of the first movable portion3. In the above-described embodiment, the first movable portion 3 isconnected to the first connection portion 5 in a cross-sectionperpendicular to the Y-axis direction and passing through the center ofthe mirror surface 7 a. In this case, the end portion of the firstmovable portion 3 is located at a boundary part between the firstmovable portion 3 and the first connection portion 5. As in theembodiment, when the first movable portion 3 includes the first portion31 and the second portion 32 surrounding the first portion 31 and themirror surface 7 a is provided on the first portion 31, the end portionof the mirror surface 7 a is located in the vicinity of the end portionof the first portion 31.

[Wiring Portion]

As illustrated in FIGS. 1 and 4, the mirror unit 100 further includes awiring portion 70 electrically connected to the optical scanning device1. The wiring portion 70 includes a plurality of (eight in this example)inner electrode pads 71, a plurality of (nine in this example) outerelectrode pads 72, and a plurality of (eight in this example) wirings73. Each of the inner electrode pad 71, the outer electrode pad 72, andthe wiring 73 is formed of, for example, a metal material such astungsten, aluminum, gold, silver, copper, or an aluminum-based alloy.

The inner electrode pad 71 is provided in an inner region (a firstregion) R1 located at the inside of the frame member 43 when viewed fromthe Z-axis direction. The inner electrode pad 71 is disposed on the base42, more specifically, the bottom surface of the depression 42 c. Theinner electrode pad 71 is disposed between the optical scanning device 1and the third wall portion 53 on the bottom surface of the depression 42c. In the mirror unit 100, a distance C1 between the optical scanningdevice 1 and the third wall portion 53 in the Y-axis direction is longerthan a distance C2 between the optical scanning device 1 and the fourthwall portion 54 in the Y-axis direction (FIG. 3). That is, the innerelectrode pad 71 is disposed between the optical scanning device 1 andthe third wall portion 53 which is distant from the optical scanningdevice 1 in the third wall portion 53 and the fourth wall portion 54. Inthe mirror unit 100, the distance between the optical scanning device 1and the first wall portion 51 in the X-axis direction is the same as thedistance between the optical scanning device 1 and the second wallportion 52 in the X-axis direction. The plurality of inner electrodepads 71 are arranged, for example, in the X-axis direction. Each of theplurality of inner electrode pads 71 is electrically connected to one ofthe electrode pads 21 a, 21 b, 22 a, and 22 b of the optical scanningdevice 1 through a wire WR.

The outer electrode pad 72 is provided in an outer region (a thirdregion) R3 located at the outside of the frame member 43 when viewedfrom the Z-axis direction. The outer electrode pad 72 is disposed on thebase 42, more specifically, the main surface 42 a. The plurality ofouter electrode pads 72 are arranged at the same intervals, for example,in the X-axis direction. The plurality of outer electrode pads 72 areused in the electrical connection to, for example, an external controldevice or the like.

As illustrated in FIG. 1, the plurality of wirings 73 respectivelyelectrically connect the inner electrode pad 71 and the outer electrodepad 72 to each other. The plurality of wirings 73 include a plurality of(four in this example) wirings 73A and a plurality of (four in thisexample) wirings 73B.

Each wiring 73A is inclined with respect to the X-axis direction and theY-axis direction when viewed from the Z-axis direction and extends in alinear shape. Each wiring 73B has a plurality of (two in this example)bent portions. Each wiring 73B includes a pair of first linear portions73Ba which are inclined with respect to the X-axis direction and theY-axis direction when viewed from the Z-axis direction and extend in alinear shape and a second linear portion 73Bb which extends in a linearshape in the X-axis direction when viewed from the Z-axis direction. Thepair of first linear portions 73Ba are located at both ends of thewiring 73B and are connected to the second linear portion 73Bb. The bentportions are formed at boundary parts between the pair of first linearportions 73Ba and the second linear portion 73Bb.

As illustrated in FIG. 4, each wiring 73 is disposed in a hole 42 eformed in the base 42 and extends inside the base 42. Each wiring 73 iselectrically connected to the inner electrode pad 71 in an inner regionR1, extends inside the base 42 in an overlapping region (a secondregion) R2 overlapping the frame member 43 when viewed from the Z-axisdirection, and leads out to the outer region R3. That is, each wiring 73includes a first portion 74 located in the inner region R1, a secondportion 75 located in the overlapping region R2, and a third portion 76located in the outer region R3.

The first portion 74 is connected to the inner electrode pad 71. In thisexample, the wiring 73 and the inner electrode pad 71 are integrallyformed (as a single member). In other words, the wiring 73 is providedto be exposed in the inner region R1 and the exposed portion constitutesthe inner electrode pad 71. The second portion 75 is connected to thefirst portion 74 and extends in a linear shape below the third wallportion 53. In other words, the wiring 73 extends inside the base 42 soas to overlap the third wall portion 53 when viewed from the Z-axisdirection in the overlapping region R2. The third portion 76 isconnected to the second portion 75, leads out from the overlappingregion R2 to the outer region R3, and is connected to the rear surfaceof the outer electrode pad 72. Although the wiring 73A of the wiring 73is illustrated in FIG. 4, the wiring 73B also extends inside the base 42similarly to the wiring 73A.

[Function and Effect]

In the mirror unit 100, a height H1 of the first wall portion 51 ishigher than a height H2 of the second wall portion 52 and the windowmember 44 is disposed on the top surface 51 a of the first wall portion51 and the top surface 52 a of the second wall portion 52 and isinclined with respect to the mirror surface 7 a. Accordingly, thetraveling direction of the light reflected by the window member 44 canbe different from the traveling direction of the light reflected by themirror surface 7 a and the light reflected by the window member 44 canbe prevented from to be noise light.

In a cross-section (FIG. 2) passing through the mirror surface 7 a andperpendicular to the first wall portion 51, the first line L1 passingthrough the first end P1 at the side of the first wall portion 51 in themirror surface 7 a and the first corner portion 61 formed at the side ofthe first wall portion 51 by the outer surface 44 a and the first sidesurface 44 c in the window member 44 intersects the first wall portion51. In the cross-section (FIG. 2), the second line L2 passing throughthe second end P2 at the side of the second wall portion 52 in themirror surface 7 a and the second corner portion 62 formed at the sideof the second wall portion 52 by the outer surface 44 a and the secondside surface 44 d in the window member 44 intersects the second wallportion 52. In a cross-section (FIG. 3) passing through the mirrorsurface 7 a and perpendicular to the third wall portion 53, the thirdline L3 passing through the third end P3 at the side of the third wallportion 53 in the mirror surface 7 a and the third corner portion 63formed at the side of the third wall portion 53 by the outer surface 44a and the third side surface 44 e in the window member 44 intersects thethird wall portion 53. In the cross-section (FIG. 3), the fourth line L4passing through the fourth end P4 at the side of the fourth wall portion54 in the mirror surface 7 a and the fourth corner portion 64 formed atthe side of the fourth wall portion 54 by the outer surface 44 a and thefourth side surface 44 f of the window member 44 intersects the fourthwall portion 54. Since the lines L1 to L4 are formed so as to intersectthe wall portions 51 to 54, each of the wall portions 51 to 54 is formedso as to be relatively thicker with respect to the window member 44.Accordingly, it is possible to support the window member 44 by the thickwall portions 51 to 54 and to prevent the damage of the window member44.

Meanwhile, when the wall portions 51 to 54 are formed to be thick, it isconceivable to widen the thickness of the wall portions 51 to 54 towardthe optical scanning device 1 from the viewpoint of miniaturization.However, in that case, the area of the portion located at the inside ofthe frame member 43 on the base 42 is narrowed. When a wiring portionfor electrical connection to the optical scanning device 1 is formed insuch a narrow portion, there is concern that defects such as shortcircuit or the like may occur in the wiring portion. In contrast, in themirror unit 100, the wiring portion 70 includes a portion (a wiring 73)extending inside the base 42 and leads outside the frame member 43. Whenthe wiring portion 70 is formed inside the base 42 in this way, it ispossible to prevent defects such as short circuit or the like in thewiring portion 70. Further, for example, compared to a case in which thewiring portion 70 is formed so as to extend along the main surface 42 aof the base 42 between the base 42 and the frame member 43, thedeterioration of the wiring portion 70 can be prevented and theinfluence of the wiring portion 70 on the bonding portion (the bondingmaterial 46) between the base 42 and the frame member 43 can beprevented. Thus, according to the mirror unit 100, it is possible toprevent the damage of the window member 44 while reducing noise lightand to improve reliability.

The thickness T44 of the window member 44 is smaller than the width W inwhich the window member 44 and the frame member 43 are bonded to eachother. Accordingly, the window member 44 can be formed to be thin andthe influence of refraction at the window member 44 can be refrained.

The first line L1 intersects the first wall portion 51 and the secondline L2 intersects the second wall portion 52. Accordingly, since boththe first wall portion 51 and the second wall portion 52 facing eachother are formed to be relatively thicker with respect to the windowmember 44, it is possible to support the window member 44 by the thickwall portions 51 and 52 and to further reliably prevent the damage ofthe window member 44. Further, the third line L3 intersects the thirdwall portion 53 and the fourth line L4 intersects the fourth wallportion 54. Accordingly, since both the third wall portion 53 and thefourth wall portion 54 facing each other are formed to be thicker thanthe window member 44, it is possible to support the window member 44 bythe thick wall portions 53 and 54 and to further reliably prevent thedamage of the window member 44.

The wiring portion 70 extends inside the base 42 so as to overlap thethird wall portion 53 when viewed from the Z-axis direction in theoverlapping region R2. When the wiring portion 70 is to be pulled outtoward the thick third wall portion 53, the above-describeddeterioration of the wiring portion 70 is likely to occur. However, inthe mirror unit 100, since the wiring portion 70 is formed inside thebase 42, deterioration of the wiring portion 70 or the like can bereliably prevented.

A distance C1 between the optical scanning device 1 and the third wallportion 53 is longer than a distance C2 between the optical scanningdevice 1 and the fourth wall portion 54 and the inner electrode pad 71is disposed between the optical scanning device 1 and the third wallportion 53 on the base 42. Accordingly, it is possible to ensure a spacefor disposing the inner electrode pad 71.

The wiring portion 70 is electrically connected to the optical scanningdevice 1 in the inner region R1 located at the inside of the framemember 43 when viewed from the Z-axis direction, extends inside the base42 in the overlapping region R2 overlapping the frame member 43 whenviewed from the Z-axis direction, and leads out to the outer region R3located at the outside of the frame member 43 when viewed from theZ-axis direction. Accordingly, it is possible to further reliablyprevent deterioration of the wiring portion 70 or the like.

The wiring portion 70 does not include a portion formed on the rearsurface 42 b of the base 42. When the rear surface 42 b of the base 42is fixed to an upper surface of a magnet (a magnetic field generatingunit) by adhering, it is preferable that the base 42 be as close aspossible to the magnet in order to ensure magnetic force acting on thefirst drive coil 11 and the second drive coil 12. Since the wiringportion 70 does not include a portion formed on the rear surface 42 b ofthe base 42, the base 42 can be close to the magnet and hence largemagnetic force acting on the first drive coil 11 and the second drivecoil 12 can be ensured.

Modified Example

In a wiring portion 70A illustrated in FIG. 6, the outer electrode pad72 and the wiring 73 are provided in the inner region R1. The outerelectrode pad 72 is disposed on the rear surface 42 b of the base 42 inthe inner region R1. The wiring 73 is connected to the rear surface ofthe inner electrode pad 71, extends inside the base 42 in a linear shapein the Z-axis direction, and is connected to the rear surface of theouter electrode pad 72. Also in such a modified example, deteriorationof the wiring portion 70 or the like can be prevented similarly to theabove-described embodiment.

In the modified example, the outer electrode pad 72 may be disposed onthe rear surface 42 b of the base 42 in the outer region R3. In thiscase, the wiring 73 may include a first portion which is connected tothe rear surface of the inner electrode pad 71, extends inside the base42 in a linear shape in the Z-axis direction, and is exposed to the rearsurface 42 b of the base 42 and a second portion which is connected tothe first portion, is provided on the rear surface 42 b so as to extendover the inner region R1, the overlapping region R2, and the outerregion R3, and is connected to the outer electrode pad 72.

In the modified example, the outer electrode pad 72 may be disposed onthe main surface 42 a of the base 42 in the outer region R3. In thiscase, the wiring 73 may include a first portion which is connected tothe rear surface of the inner electrode pad 71, extends inside the base42 in a linear shape in the Z-axis direction, and is exposed to the rearsurface 42 b of the base 42, a second portion which is connected to thefirst portion and is provided on the rear surface 42 b so as to extendover the inner region R1, the overlapping region R2, and the outerregion R3, and a third portion which is connected to the second portion,extends inside the base 42 in a linear shape in the Z-axis direction,and is connected to the rear surface of the outer electrode pad 72.

The present disclosure is not limited to the embodiment and the modifiedexample above. For example, the materials and shapes of the componentsare not limited to the materials and shapes described above and variousmaterials and shapes can be adopted. The thicknesses T51 to T54 of thewall portions 51 to 54 may be different from each other. The wiring 73may be electrically connected to the inner electrode pad 71 in the innerregion R1, extend inside the base 42 in the overlapping region R2, andlead out to the outer region R3 and a part of the wiring 73 may beconfigured as a surface wiring formed along the surface of the base 42.In the optical scanning device 1 of the embodiment, the movable portion10 is driven by the electromagnetic force, but the movable portion 10may be driven by an electrostatic force or a piezoelectric element.

In the above-described embodiment, the third wall portion 53 can beregarded as a first reference wall portion and the fourth wall portion54 can be regarded as a second reference wall portion. In this case, thethird wall portion 53, the third end P3, the third side surface 44 e,the third corner portion 63, and the third line L3 respectivelycorrespond to the first wall portion, the first end, the first sidesurface, the first corner portion, and the first line and the fourthwall portion 54, the fourth end P4, the fourth side surface 44 f, thefourth corner portion 64, and the fourth line L4 respectively correspondto the second wall portion, the second end, the second side surface, thesecond corner portion, and the second line. In the above-describedembodiment, the third wall portion 53 can be regarded as the secondreference wall portion and the fourth wall portion 54 can be regarded asthe third reference wall portion.

In the above-described embodiment, the first wall portion 51 can beregarded as the first reference wall portion and the second wall portion52 can be regarded as the second reference wall portion. In this case,the first wall portion 51, the first end P1, the first side surface 44c, the first corner portion 61, and the first line L1 respectivelycorrespond to the first wall portion, the first end, the first sidesurface, the first corner portion, and the first line and the secondwall portion 52, the second end P2, the second side surface 44 d, thesecond corner portion 62, and the second line L2 respectively correspondto the second wall portion, the second end, the second side surface, thesecond corner portion, and the second line. In this case, the distancebetween the optical scanning device 1 and the first wall portion 51 maybe longer than the distance between the optical scanning device 1 andthe second wall portion 52 and the inner electrode pad 71 may bedisposed between the optical scanning device 1 and the first wallportion 51 on the base 42. That is, the inner electrode pad 71 may bedisposed between the optical scanning device 1 and the first wallportion 51 distant from the optical scanning device 1 in the first wallportion 51 and the second wall portion 52. Also in this case, it ispossible to ensure a space for disposing the inner electrode pad 71.Further, since the first wall portion 51 is separated from the opticalscanning device 1 compared to the second wall portion 52, it is possibleto prevent the light reflected by the mirror surface 7 a from beinginterrupted by the first wall portion 51 higher than the second wallportion 52. In the above-described embodiment, the first wall portion 51can be regarded as the second reference wall portion and the second wallportion 52 can be regarded as the first reference wall portion.

In the above-described embodiment, all of the conditions (1) to (4)below are met. However, at least one of the conditions (1) to (4) belowmay be met and the others may not be met.

(1) In the cross-section of FIG. 2, the first line L1 intersects thefirst wall portion 51.(2) In the cross-section of FIG. 2, the second line L2 intersects thesecond wall portion 52.(3) In the cross-section of FIG. 3, the third line L3 intersects thethird wall portion 53.(4) In the cross-section of FIG. 3, the fourth line L4 intersects thefourth wall portion 54.

The window member 44 may be provided with a notch. The notch may beformed in, for example, the outer surface 44 a and may extend along theedge portion of the outer surface 44 a. The notch may be formed in, forexample, a rectangular cross-sectional shape. In this case, the windowmember 44 includes a first corner portion formed at the side of thefirst wall portion 51 by the outer surface 44 a and the inner surface ofthe notch, a second corner portion formed at the side of the second wallportion 52 by the outer surface 44 a and the inner surface of the notch,a fifth corner portion (another first corner portion) formed by theinner surface of the notch and the first side surface 44 c, and a sixthcorner portion (another second corner portion) formed by the innersurface of the notch and the second side surface 44 d in thecross-section of FIG. 2. Further, the window member 44 includes a thirdcorner portion formed at the side of the third wall portion 53 by theouter surface 44 a and the inner surface of the notch, a fourth cornerportion formed at the side of the fourth wall portion 54 by the outersurface 44 a and the inner surface of the notch, a seventh cornerportion (another third corner portion) formed by the inner surface ofthe notch and the third side surface 44 e, and an eighth corner portion(another fourth corner portion) formed by the inner surface of the notchand the fourth side surface 44 f in the cross-section of FIG. 3. In thiscase, at least one of the conditions (5) to (8) below may be met. (5) Inthe cross-section of FIG. 2, a line passing through the first cornerportion and the first end P1 at the side of the first wall portion 51 inthe mirror surface 7 a intersects the first wall portion 51. (6) In thecross-section of FIG. 2, a line passing through the second cornerportion and the second end P2 at the side of the second wall portion 52in the mirror surface 7 a intersects the second wall portion 52. (7) Inthe cross-section of FIG. 3, a line passing through the third cornerportion and the third end P3 at the side of the third wall portion 53 inthe mirror surface 7 a intersects the third wall portion 53. (8) In thecross-section of FIG. 3, the fourth line L4 passing through the fourthcorner portion and the fourth end P4 at the side of the fourth wallportion 54 in the mirror surface 7 a may intersect the fourth wallportion 54. Accordingly, similarly to the above-described embodiment,each of the wall portions 51 to 54 can be formed to be thick. At leastone of the conditions (9) to (12) below may be met. (9) In thecross-section of FIG. 2, a line passing through the first end P1 and thefifth corner portion intersects the first wall portion 51. (10) In thecross-section of FIG. 2, a line passing through the second end P2 andthe sixth corner portion intersects the second wall portion 52. (11) Inthe cross-section of FIG. 3, a line passing through the third end P3 andthe seventh corner portion intersects the third wall portion 53. (12) Inthe cross-section of FIG. 3, a line passing through the fourth end P4and the eighth corner portion intersects the fourth wall portion 54.Also in this condition, each of the wall portions 51 to 54 can be formedto be thick. When the conditions (9) to (12) above are met, theconditions (5) to (8) above may not be met. In this case, since theconditions (9) to (12) above are met, each of the wall portions 51 to 54can be formed to be thick. Further, since the conditions (5) to (8)above are not met, it is possible to prevent the light reflected by themirror surface 7 a from being interrupted by each of the wall portions51 to 54 and to use the entire outer surface 44 a of the window member44 for optical scanning. The outer surface 44 a of the window member 44means a surface facing the side opposite to the optical scanning device1 and includes the inner surface of the notch.

What is claimed is:
 1. A mirror unit comprising: a base; an opticalscanning device that includes a movable portion and a mirror surfaceprovided on the movable portion and is disposed on a surface of thebase; a frame member disposed on the surface of the base so as tosurround the optical scanning device when viewed from a first direction;and a window member disposed on the frame member so as to cover anopening of the frame member, wherein the frame member includes a firstwall portion and a second wall portion which face each other in a seconddirection perpendicular to the first direction, wherein a height of thefirst wall portion from the surface of the base is higher than a heightof the second wall portion from the surface of the base, wherein thewindow member is disposed on a top surface of the first wall portion anda top surface of the second wall portion and is inclined with respect toa region in the surface of the base, wherein the optical scanning deviceis disposed on the region, and wherein a distance between the opticalscanning device and the first wall portion is greater than a distancebetween the optical scanning device and the second wall portion whenviewed from the first direction.
 2. The mirror unit according to claim1, wherein the window member is formed in a plate shape.
 3. The mirrorunit according to claim 1, wherein the base is bonded to the framemember by a bonding material.
 4. The mirror unit according to claim 1,wherein the base and the frame member are integrally formed so as toconfigure a single member.
 5. The mirror unit according to claim 1,wherein in a cross-section passing through the mirror surface andparallel to both the first direction and the second direction, at leastone of a thickness of the first wall portion and a thickness of thesecond wall portion in the second direction is thicker than a thicknessof the window member.
 6. The mirror unit according to claim 1, whereinin a cross-section passing through the mirror surface and parallel toboth the first direction and the second direction, a thickness of thefirst wall portion in the second direction is greater than a distancebetween the optical scanning device and the first wall portion in thesecond direction.
 7. The mirror unit according to claim 1, furthercomprising a wiring portion electrically connected to the opticalscanning device, wherein the wiring portion includes an electrode paddisposed on the surface of the base and between the optical scanningdevice and the first wall portion.
 8. The mirror unit according to claim1, further comprising a wiring portion electrically connected to theoptical scanning device, wherein the wiring portion includes a partextending inside the base in a region located inside the frame memberwhen viewed from the first direction.
 9. The mirror unit according toclaim 1, further comprising a wiring portion electrically connected tothe optical scanning device, wherein the wiring portion includes alinear potion that is inclined with respect to a third directionperpendicular to both the first direction and the second direction andextends in a linear shape at a region located inside the frame memberwhen viewed from the first direction.
 10. The mirror unit according toclaim 1, wherein the optical scanning device further includes a supportportion, wherein the movable portion including: a first movable portion;a second movable portion that surrounds the first movable portion with agap and is surrounded by the support portion with a gap when viewed fromthe first direction; a pair of first connection portions connecting thefirst movable portion to the second movable portion so that the firstmovable portion is swingable around a first axis; and a pair of secondconnection portions connecting the second movable portion to the supportportion so that the second movable portion is swingable around a secondaxis perpendicular to the first axis, wherein the optical scanningdevice is disposed so that the first axis is parallel to the seconddirection and the second axis is parallel to a third directionperpendicular to both the first direction and the second direction. 11.The mirror unit according to claim 1, wherein the optical scanningdevice further includes a support portion, wherein the movable portionincluding: a first movable portion; a second movable portion thatsurrounds the first movable portion with a gap and is surrounded by thesupport portion with a gap when viewed from the first direction; a pairof first connection portions connecting the first movable portion to thesecond movable portion so that the first movable portion is swingablearound a first axis; and a pair of second connection portions connectingthe second movable portion to the support portion so that the secondmovable portion is swingable around a second axis perpendicular to thefirst axis, wherein the first movable portion includes a first portionon which the mirror surface is formed, a second portion surrounding thefirst portion with a gap, and a connection portion connecting the firstportion to the second portion.
 12. The mirror unit according to claim10, wherein a length of the second movable portion in the seconddirection is longer than a length of the second movable portion in thethird direction when viewed from the first direction.
 13. The mirrorunit according to claim 1, wherein a depression is provided at a regionin the surface of the base, wherein the region faces the movable portionof the optical scanning device in the first direction.
 14. The mirrorunit according to claim 1, wherein the optical scanning device furtherincludes a support portion which supports the movable portion, andwherein the support portion is fixed to the surface of the base.